Eruption pattern of the maxillary canines: features indicating treatment needs as seen in PTG at the late mixed stage-Part II.

AIM: To describe features of maxillary permanent canines in the late mixed stage as seen in panoramic radiograph (PTG) that later needed treatment to erupt into the oral cavity and to compare them with naturally erupted canines. METHODS: The cross-sectional part of this retrospective register-based study consisted of 1454 PTGs of children (mean age 9.3 years) living in Eastern Finland, while the longitudinal part involved patient data on 184 treated maxillary canines. The variables examined were treatment needs, overlapping and inclination of the maxillary canines, the development stage of the canines and lateral incisors and dental age. RESULTS: Only 11.6% of the maxillary canines needed treatment, including interceptive procedures. The treated canines significantly more often had overlapping (p < 0.001), larger inclination (p = 0.001) and incomplete lateral incisors (p = 0.002) than did the naturally erupted canines. The children treated significantly more often had a delayed dental age (p = 0.035). Clear overlapping was closely associated with all treatment modalities, whereas some overlapping and a large inclination angle (≥ 25°) were associated especially in cases of late treatment. An incomplete lateral incisor and delayed dental age were associated with treatment. CONCLUSION: An association with treatment needs was found especially in the case of overlapping and a large inclination angle of the maxillary canine a couple of years before eruption into the oral cavity. These features can be early signs and indications for instant or later treatment of a maxillary canine and underline the importance of monitoring space conditions and erupting canines.

Eruption pattern of the maxillary canines: features of natural eruption seen in PTG at the late mixed stage-Part I.

AIM: To describe the variation of eruption pattern of maxillary canines in the late mixed stage of dentition seen in PTG when eruption was later natural. METHODS: Material for this longitudinal and retrospective register-based study consisted of 1454 PTGs of children living in Eastern Finland (mean age 9.3 years, SD 0.6). Natural eruption of a canine consisted of 744 PTGs (336 girls and 408 boys) including 1488 maxillary canines. The variables examined were treatment/natural eruption, overlapping, inclination, dental age, developmental stage of the canine and lateral incisor. RESULTS: Only 2.0% of maxillary canines had clear overlapping and 56.2% no overlapping was detected at the age of 8.5-10.5 years. Large inclination angle (≥ 25°) was found for 5.5% of examined canines. Overlapping of canine with lateral incisor root decreased as the development of canine root exceeded 1/3. Larger inclinations occurred at earlier stages but decreased significantly as the root developed from 1/3 to 1/2. Mean inclination was significantly larger at children with normal dental age and/or incomplete lateral incisors when overlapping occurred. Regardless overlapping mean inclination was larger if dental age was delayed and/or lateral incisors incomplete. CONCLUSION: Some overlapping and larger inclination in maxillary canine are features of normal eruption pattern at an earlier stage of canine development and while lateral incisor is incomplete in PTG (8.5-10.5 years). In addition to the overlapping and inclination, stages of canine and lateral incisor root as well as dental age should be observed radiologically when evaluating erupting maxillary canine in children of this age.

GWAS Identifies New Loci for Painful Temporomandibular Disorder: Hispanic Community Health Study/Study of Latinos.

Temporomandibular disorder (TMD) is a musculoskeletal condition characterized by pain and reduced function in the temporomandibular joint and/or associated masticatory musculature. Prevalence in the United States is 5% and twice as high among women as men. We conducted a discovery genome-wide association study (GWAS) of TMD in 10,153 participants (769 cases, 9,384 controls) of the US Hispanic Community Health Study/Study of Latinos (HCHS/SOL). The most promising single-nucleotide polymorphisms (SNPs) were tested in meta-analysis of 4 independent cohorts. One replication cohort was from the United States, and the others were from Germany, Finland, and Brazil, totaling 1,911 TMD cases and 6,903 controls. A locus near the sarcoglycan alpha ( SGCA), rs4794106, was suggestive in the discovery analysis ( P = 2.6 × 106) and replicated (i.e., 1-tailed P = 0.016) in the Brazilian cohort. In the discovery cohort, sex-stratified analysis identified 2 additional genome-wide significant loci in females. One lying upstream of the relaxin/insulin-like family peptide receptor 2 ( RXP2) (chromosome 13, rs60249166, odds ratio [OR] = 0.65, P = 3.6 × 10-8) was replicated among females in the meta-analysis (1-tailed P = 0.052). The other (chromosome 17, rs1531554, OR = 0.68, P = 2.9 × 10-8) was replicated among females (1-tailed P = 0.002), as well as replicated in meta-analysis of both sexes (1-tailed P = 0.021). A novel locus at genome-wide level of significance (rs73460075, OR = 0.56, P = 3.8 × 10-8) in the intron of the dystrophin gene DMD (X chromosome), and a suggestive locus on chromosome 7 (rs73271865, P = 2.9 × 10-7) upstream of the Sp4 Transcription Factor ( SP4) gene were identified in the discovery cohort, but neither of these was replicated. The SGCA gene encodes SGCA, which is involved in the cellular structure of muscle fibers and, along with DMD, forms part of the dystrophin-glycoprotein complex. Functional annotation suggested that several of these variants reside in loci that regulate processes relevant to TMD pathobiologic processes.

Can the results of the OSCE predict the results of clinical assessment in dental education?

INTRODUCTION: The aims of this study were to evaluate the correlation between the results of the objective structured clinical examination (OSCE) and clinical assessment and to test the reliability of OSCE test stations. MATERIAL AND METHODS: All 4th year undergraduate dental students (n = 47, 100%) attended the OSCE in April 2010. The students were divided into two groups (morning group, group 1; afternoon group, group 2). Groups 1 and 2 were also divided into two subgroups that attended the stations in two concurrent sessions (A and B). The OSCE included 12 10-min test stations. Clinical assessment was based on long-term observation during the semesters. The disciplines assessed were cross-infection control, endodontics, paediatric dentistry, periodontology, prosthodontics and restorative dentistry. RESULTS: Statistical analysis using Cronbach's alpha indicated good reliability of the OSCE. The correlation between the results of the OSCE and clinical assessment in the 4th year was statistically significant in cross-infection control (ρ = 0.340, P = 0.022), endodontics (ρ = 0.298, P = 0.047), prosthodontics (ρ = 0.296, P = 0.048) and restorative dentistry (ρ = 0.376, P = 0.011). Clinical assessment in the 5th year correlated with the OSCE results statistically significant in restorative dentistry (ρ = 0.522, P = 0.001). CONCLUSION: Both the OSCE and constant longitudinal assessment are needed in clinical assessment, as they both play an important role in the overall assessment.

Prevalence of infraocclusion of primary molars determined using a new 2D image analysis methodology.

BACKGROUND: The reported prevalence of infraocclusion varies widely, reflecting differences in definitions and measurement/scoring approaches. This study aimed to quantify the prevalence and extent of infraocclusion in singletons and twins during the late mixed dentition stage of dental development using a new diagnostic imaging method and objective criteria. The study also aimed to determine any associations between infraocclusion and gender, arch type, arch side and tooth type. METHODS: Two samples were analysed, 1454 panoramic radiographs of singletons and 270 dental models of twins. Both samples ranged in age from 8 to 11 years. Adobe Photoshop CS5 was used to measure the extent of infraocclusion. Repeatability tests showed systematic and random errors were small. RESULTS: The prevalence in the maxilla was low (<1%), whereas the prevalence in the mandible was 22% in the singleton sample and 32% in the twin sample. The primary mandibular first molar was affected more often than the second molar. There was no significant difference in the expression between genders or sides. CONCLUSIONS: A new technique for measuring infraocclusion has been developed with high intra- and interoperator reproducibility. This method should enhance early diagnosis of tooth developmental abnormalities and treatment planning during the late mixed dentition stage of development.

Root lengths in 47,XYY males' permanent teeth.

Studies on individuals with sex chromosome anomalies have demonstrated the promoting effect of the Y chromosome on tooth crown enamel and dentin growth. The present research investigated permanent tooth root lengths in 47,XYY males. The measurements were made from panoramic radiographs. The results indicate longer tooth roots in 47,XYY males compared with those in control males and females. The promoting effect of the Y chromosome on dental growth thus continues in the form of root dentin after the completion of crown growth. The results, together with those on tooth crown sizes in 47,XYY males, suggest that growth excesses are evident and final, beginning a few months after birth and continuing up to the age of 14 years, at least. The excess root dentin growth in 47,XYY males, as well as sexual dimorphism in the growth of crown and root dentin, might be caused by the same factor on the Y chromosome.